1. Field of the Invention
The present invention relates to a method of producing acidic or alkaline electrolyzed water, and an electrolyzed water producing apparatus therefor.
2. Description of the Related Art
Conventionally, there has been known an electrolyzed water producing method which includes: supplying raw water to a pair of electrolytic chambers opposed to each other across an intervening ion permeable diaphragm, such as an anion permeable membrane; and applying voltage to a pair of electrodes disposed in the respective electrolytic chambers, to electrolyze the raw water supplied to the electrolytic chambers. When a chloride salt, such as sodium chloride, is previously added as an electrolyte to the raw water, this method is capable of obtaining acidic electrolyzed water containing hypochlorous acid from the anode-side electrolytic chamber and alkaline electrolyzed water from the cathode-side electrolytic chamber.
Such acidic electrolyzed water exhibits a potent bactericidal action based on the oxidizing power or the like of the hypochlorous acid and hence can be used for disinfection or a like purpose in medical institutions and the like. Such alkaline electrolyzed water can be used for cleaning or a like purpose. However, there are relatively few applications that require both of acidic electrolyzed water and alkaline electrolyzed water at the same time. For this reason, in general, either acidic electrolyzed water or alkaline electrolyzed water is used only, while the other is discarded as waste water. In such a case, a problem arises from the viewpoint of resources saving because a half of the total amount of the raw water is discarded as waste water.
In attempt to solve such a problem, an electrolyzed water producing method has been proposed which includes: supplying raw water to only one electrolytic chamber while circulating an aqueous solution containing an electrolyte (hereinafter will be briefly referred to as “aqueous electrolyte solution”) to the other electrolytic chamber; electrolyzing the raw water and the aqueous electrolyte solution; and taking out electrolyzed water produced in the electrolytic chamber supplied with the raw water (see Japanese Patent Laid-Open No. H9-220572 for example).
According to this method, when, for example, acidic electrolyzed water is needed, electrolysis is performed using the electrode disposed in the electrolytic chamber supplied with the raw water as an anode and the electrode disposed in the electrolytic chamber to which the aqueous electrolyte solution is circulated as a cathode. As a result, acidic electrolyzed water is produced in the electrolytic chamber supplied with the raw water (i.e., anode-side electrolytic chamber) and taken out therefrom. Though alkaline electrolyzed water is produced in the other electrolytic chamber, the alkaline electrolyzed water is circulated together with the aqueous electrolyte solution and hence is not discarded as waste water. Thus, the resources can be utilized effectively.
With the method described in the patent document noted above, however, the intensity of generation of electrolytic current varies depending on the electric conductivity of the raw water supplied since the raw water is supplied to only one of the electrolytic chambers while the aqueous electrolyte solution produced during electrolysis is circulated to the other electrolytic chamber. Moreover, the quality of raw water varies greatly in accordance with geographic regions. For example, water obtained from a certain region for use as the raw water exhibits a very low electric conductivity of not more than 10 mS/m, while water obtained from another region exhibits a high electric conductivity of from 40 to 50 [mS/m]. For this reason, when electrolytic current is difficult to generate, the method of the aforementioned patent document is required to raise the voltage applied across the pair of electrodes (i.e., electrolytic voltage) in order to obtain electrolyzed water having a desired property by electrolysis. Accordingly, the method has to use a large-capacity electrolysis power source in order to accommodate a diversity of geographic regions, thus resulting in an inconvenience that the size and weight of the electrolyzed water producing apparatus and the cost are difficult to reduce.